A motorcycle in which an engine is used as a part of a body frame is known. For example, there is a motorcycle in which a body frame extends from a head pipe slantingly downward to the rear along an approximately straight line in a side view, and a lower end portion of the body frame is joined to a case of a horizontal opposed engine Japanese Patent Laid-Open Publication No. Heisei 10-329776. Further, there is a motorcycle in which the rear side of a front frame is bifurcated and joined to front and rear portions of a cylinder head of a forward tilted engine Japanese Patent Publication No. 2593868.
In the form where the horizontal opposed engine is supported, the body frame becomes too long and therefore the weight of the body frame increases. Thus, there is a need to reduce the length of the body frame as much as possible from the viewpoint of weight reduction of the body. On the other hand, in the form where the forward tilted engine is supported, the cylinder head is supported. Thus, large force is applied to the cylinder head and therefore it is required to increase strength of the cylinder head by increasing the size thereof, in order to prevent distortion and the like. Thus, the size and weight of the engine are increased by just that much. Therefore, there is a need to reduce the required strength so as to reduce the size and weight of the cylinder head. In addition, there is a need to effectively use the space between the head pipe and the cylinder head by reducing the size and weight of the cylinder head. It is an object of the present invention to realize these needs.